According to ESRB, this game contains: Comic Mischief, Mild Violence
Parents shouldn't be too worried about Mister Mosquito since the bulk of the game is flying around and doing what a mosquito does. I'd imagine that most kids would probably get a big kick out of it and have some good laughs. The only violence in the game comes from the humans who will try to swat, spray or smash the games winged hero if he's discovered. There's no graphic blood or gore (insect or otherwise), and its all highly tame. The bathroom level might be a little questionable for some since it features the family's teenage daughter soaking in the tub, but there is no explicit nudity although there is some minor cleavage. If you've ever seen MTV, you've seen worse than what's in this game.
Fans of weirdness will have a field day with Mister Mosquito. Games literally do not come any stranger or more offbeat than this one. It's also loaded with lots of cultural Japanese touches and their distinctive sense of humor. If you are a fan of strange, Japanese-themed games or just looking for something that's way, way, way outside of the norm, you cant go wrong with Mister Mosquito.
Deaf and hard of Hearing gamers should be aware that the games cut-scenes between levels revolve around family meetings and their plans to assassinate Mister Mosquito. During these conversations as well as the games intro and ending, there is no text accompanying the spoken dialogue.